Generally known examples of geodesic measuring devices are the theodolite or the total station. Geodesic measuring devices are used for determining distances and for simultaneously acquiring corresponding angles with respect to target points. Such systems are in widespread use primarily in the field of landscape surveying or for positioning tasks in industry. Both areas of use demand the exact determination of the variables of distance and angle over in some instances large distances, in order e.g. to be able to precisely plan and implement subsequent building development of a surveyed terrain or in order to control a machine incorporated into a production process.
One known extension of these measuring devices is combination with an image recording unit, usually integrated into the device. Thus, in addition to the variables determined, e.g. a camera can be used to acquire images of an environment in which the target points are situated. This combination opens up the possibility, inter alia, of carrying out a measurement e.g. by means of image-assisted target point seeking. Moreover, the recording of an optical image makes it possible to bring about a target identification or target tracking and thus a further facilitation and automation of the measuring process. An automatic target tracking is known from EP 2 141 450, for example, wherein a sighting direction of a measuring station is automatically aligned with a target on the basis of a processed image.
Furthermore, an image of a recorded environment to be measured can be displayed on a display fitted to the measuring device. By means of an input unit, a user is thus enabled to select specific points of interest on the image and to determine the exact positions of the points with the aid of the distance and angle measuring devices incorporated in the measuring device.
EP 1 314 959 and WO 2004/036145 disclose for example geodesic measuring devices comprising an electronic display and control device which enable screen-based operation.
In a two-dimensional representation of an optical image, it is accordingly possible to define points with respect to which a measurement, i.e. the determination of distance and/or angle, is effected. On the basis of an image that can be acquired by various recording means, targets can be identified and tracked by means of image processing methods, such that an automatic measurement is possible in principle on this basis thus provided. In addition, with such an embodiment—by means of the arrangement of at least one camera with an extended acquisition spectrum—ranges and object properties which are outside the visual accessibility of the human eye can be made accessible to the measurement.
By means of these geodesic measuring devices, points selected beforehand, e.g. on a display, can be sighted, moved to and subsequently measured. For the user of such a device, this significantly simplifies the operability and affords the major advantage with regard to ergonomics that the device need not necessarily be aligned through an eyepiece, but rather can be controlled on the basis of the display or via a remote control.
What is disadvantageous, however, is that only angle and distance data can be ascertained with respect to an appropriate point and, furthermore, no further information about e.g. the object on which the point is situated can be acquired. Furthermore, no assignment or linking of position information to further image-based object- or target-point-related data takes place.
Additional information about an object or the surface thereof can be acquired e.g. on the basis of a camera-recorded color value or else by means of a thermal imaging camera. By means of this information, it is possible to derive specific object properties or properties of at least parts of objects. By way of example, thermal imaging cameras can be used for identifying irregularities in a heat distribution or heat leaks and it is thereby possible to ascertain such locations e.g. at buildings. A thermal detector can also be used in fire fighting—for finding a fire source—or for target identification when darkness prevails.
One problem in the course of using a thermal imaging camera that can be handheld arises when an exact position of a conspicuous feature identified by the camera or e.g. the dimensioning of said conspicuous feature is intended to be determined. Such a positioning or determination of the extent cannot be performed solely from a manually acquired thermal image, which can then usually be displayed on a display at the camera. However, exact position determination for such conspicuous features would be desirable inter alia in the case of e.g. construction measures to be performed for the purpose of improving insulation or repair work.